1. Field of the Invention
The present invention relates to a pipe joint, a pipe connection structure possessing the structure of the pipe joint, and a method for connecting the joint and a pipe. It particularly relates to a pipe joint, for which execution of work is simple and high airtightness and reliability can be achieved without using a flame.
2. Description of the Related Art
Conventionally, for connecting a joint for metal piping and a metal pipe, metal O-ring crimping or blazing, etc., which are used for transmitting a pressurized gas or fluid through, have been used.
Particularly, in the case of piping for coolant for an air conditioner, because high-temperature and high-pressure gas needs to be maintained in complete airtightness for a long period of time, a highly reliable brazing method has been used. The brazing method, however, has problems such that it can be used only by gas welding technicians because a flame is used, and special skills are required. In recent years, to improve safety inside work sites for piping, using a flame is starting to be avoided.
For this reason, in place of brazing, a metal O-ring crimping method has been adopted in many places. By the joint structure of the metal O-ring crimping method, as shown in FIG. 11, the airtightness and pressure resistance of piping are achieved by: squeezing a wedge-shaped O-ring 3 into a gap provided between a pipe joint 1 and a metal pipe 2 using strong pressure, and bending and deforming the metal O-ring 3 in a direction of the inner diameter by fixing and tightening the O-ring with a cap nut 4, and at the same time letting it cut into the pipe joint 1 and the metal pipe 2.
The pipe connection structure of the above-mentioned metal O-ring crimping method, however, has a problem that great force is required for the work. Particularly, in the case of piping with large bore sizes, because working tools become large, it is difficult to work in a small indoor site. Additionally, as indicated by the facts that connection of a metal pipe joint and a pipe, which requires complete airtightness, conventionally has been done by brazing, it can be said that achieving complete airtightness by the metal O-ring crimping method is difficult due to its structure.
The present invention was accomplished in consideration of the above-mentioned situation. One of its objects is to provide a structure and method for connecting a pipe joint and a pipe without using a flame, which can achieve airtightness and reliability equal to those achieved by the brazing method, as well as excellent workability.
The first embodiment of the present invention to achieve the above-mentioned objects is a pipe joint for connecting a pipe using an anaerobic adhesive. This embodiment is characterized in that it has a double pipe structure and a tapered surface. The double pipe structure is formed with an inner pipe fitting into the inner circumference of the pipe end integrated with an outer pipe fitting into the outer circumference of the pipe end. The tapered surface is formed with at least one of the inner pipe or the outer pipe approaching the other.
The second embodiment of the present invention is the pipe joint described in the first embodiment. This embodiment is characterized in that it has a cap with a tube portion, a lid portion, an adhesive-filling slit and an air escape slit. The tube portion is inserted in a gap provided between the inner pipe and the outer pipe. The lid portion covers one end of the tube portion. The adhesive-filling slit is formed on the tube portion and linked with the gap. The air escape slit is formed on the tube portion and linked with the gap.
The third embodiment of the present invention is a structure for connecting a pipe using an anaerobic adhesive. This embodiment is characterized in that it has a double pipe structure and a tapered surface. The double pipe structure is formed with an inner pipe fitting into the inner circumference of the pipe end integrated with an outer pipe fitting into the outer circumference of the pipe end. The tapered surface is formed with at least one of the inner pipe or the outer pipe approaching the other. It is also characterized in that the pipe is fixed by the anaerobic adhesive that is hardened by pressing the pipe end against the tapered surface to narrow a gap between the pipe and the inner pipe or the outer pipe.
The fourth embodiment of the present invention is a method for connecting a pipe. This embodiment is characterized in that a pipe joint with a double pipe structure and a tapered surface is used. The double pipe structure is formed with an inner pipe fitting into the inner circumference of the pipe end integrated with an outer pipe fitting into the outer circumference of the pipe end. The tapered surface is formed with at least one of the inner pipe or the outer pipe approaching the other. It is also characterized in that an anaerobic adhesive is filled in the gap between the pipe and the inner pipe or the outer pipe, and is hardened by narrowing the gap by pressing a pipe into the gap in the pipe joint to push the pipe end against the tapered surface.
The fifth embodiment of the present invention is a pipe joint for connecting a pipe by an adhesive. This embodiment is characterized in that it comprises (1) a main body with a double pipe structure that is formed with an inner pipe fitting into an inner circumference of the pipe end integrated with an outer pipe fitting into the outer circumference of the pipe end with a gap between them, (2) O-rings provided between each end of the outer pipe and the pipe, and (3) O-ring locking materials holding in place the O-rings, which are supported by the outer pipe.
In the sixth embodiment of the present invention, the above-mentioned O-ring is a protruding portion in a circular shape extending in the direction of an inner side of the double structure and possesses a protruding portion to be inserted between the outer circumference of the pipe and the inner circumference of the outer pipe.